Patent application title: RESIDUAL FUEL OIL ADDITIVE

Abstract:

Fuel additives are disclosed for high-asphaltene carbonaceous fuels such
as residual fuel oil or coal. Such additives provide improved combustion
characteristics. Such improved combustion characteristics include one or
both of improved efficiency and decreased emissions of pollutants. In
particular, the fuel additives include an extract from a plant such as
fescue, alfeque, or alfalfa, and optionally, an organometallic compound.
The use of a fuel additive including both a plant extract and an
organometallic compound is particularly useful in improving the
combustion characteristics of fuels with particularly high asphaltene
content.

Claims:

2. The fuel additive of claim 1 wherein the plant extract is an extract of
a plant from the Leguminosae family.

3. The fuel additive of claim 2 wherein the plant extract is selected from
the group consisting of fescue extract, alfeque extract, alfalfa extract,
and combinations thereof.

4. The fuel additive of claim 3 wherein the organometallic compound is a
hydrocarbon-soluble organometallic compound containing at least one metal
selected from the first and second row transition metals.

5. The fuel additive of claim 4 wherein the metal of the organometallic
compound is iron

6. The fuel additive of claim 5 wherein the organometallic compound is
selected from the group consisting of iron pentacarbonyl, iron
naphthenate, ferrocene, and combinations thereof.

7. The fuel additive of claim 1 wherein the organometallic compound is a
hydrocarbon-soluble organometallic compound containing at least one metal
selected from the first and second row transition metals.

8. The fuel additive of claim 7 wherein the metal of the organometallic
compound is iron

9. The fuel additive of claim 8 wherein the organometallic compound is
selected from the group consisting of iron pentacarbonyl, iron
naphthenate, ferrocene, and combinations thereof.

10. The fuel additive of claim 1 further comprising an oil-soluble
carrier.

11. The fuel additive of claim 10 wherein the oil-soluble carrier is an
aromatic solvent.

12. The fuel additive of claim 10 wherein the plant extract is provided in
an amount from about 0.01 wt. % to about 10 wt. % of the fuel additive.

13. The fuel additive of claim 12 wherein the plant extract is provided in
an amount from about 0.05 wt. % to about 5 wt. % of the fuel additive.

14. The fuel additive of claim 13 wherein the plant extract is provided in
an amount of about 0.5 wt. % of the fuel additive.

15. The fuel additive of claim 1 further comprising a material selected
from meadowfoam oil, a carotenoid, an anti-oxidant, and combinations
thereof.

16. The fuel additive of claim 1 further comprising meadowfoam oil, a
carotenoid, and an anti-oxidant.

56. The fuel of claim 42 wherein the plant extract is extracted by a
hydrocarbon-soluble polar or nonpolar solvent.

Description:

CROSS-REFERENCE TO RELATED APPLICATION

[0001]This application claims the benefit of Provisional Application No.
60/753,318, filed Dec. 21, 2005, the entire disclosure of which is
incorporated by reference.

TECHNICAL FIELD

[0002]The invention pertains to fuel additives for carbonaceous fuels
having high asphaltene content such as residual fuel oil and coal.
Benefits from the use of such fuel additives may include one or more of
reduced particulate matter emissions, reduced nitrogen oxide emissions,
and improved combustion efficiency.

BACKGROUND OF THE INVENTION

[0003]Carbonaceous fuels with high asphaltene content such as residual
fuel oil and coal tend to liberate large amounts of energy on combustion,
and therefore, find utility in applications where a low cost, high energy
fuel is desired. However, such high-asphaltene carbonaceous fuels
generally burn with less efficiency than other hydrocarbon fuels, and may
often contain quantities of undesirable compounds that limit combustion
and result in elevated levels of pollutants.

[0005]The compounds referred to as "asphaltenes" generally include
polynuclear aromatics and/or polycyclic materials. While certain parts of
the world such as North America tend to have specifications which limit
the amount of asphaltenes in fuels such as residual fuel oils, such fuels
still have relatively high levels of asphaltenes compared to other,
lighter hydrocarbon fuels. For example, in the United States,
specifications limit the asphaltene content of residual fuel oil to less
than about 8 wt. %. However, in other parts of the world, asphaltene
specifications tend to be either non-existent, or significantly higher
than those in North America. Therefore, residual fuel oils in other parts
of the world may have asphaltene contents of 10 wt. % or higher. As a
fairly heavy carbonaceous fuel, coal also tends to have high
concentrations of ring structures which may include anthracene and
phenanthrene which for purposes of this specification are to be included
as "asphaltenes." It should be noted that as coal becomes "older," more
of such rings form and become interconnected such that coal can also be
considered a high-asphaltene carbonaceous fuel. For purposes of this
specification, the term "high-asphaltene carbonaceous fuel" is intended
to broadly encompass carbonaceous fuels which have asphaltene content of
at least 4 wt %.

[0006]Examples of the pollutants that can result from the combustion of
high-asphaltene carbonaceous fuels include ozone, particulate matter
(PM), carbon monoxide, nitrogen oxides (NOx), sulfur dioxide,
polynuclear aromatic compounds, and soluble organic fractions. In the
United States, numerous state and national agencies have or are adopting
ambient air quality standards which may require reduced emissions from
the combustion of high-asphaltene carbonaceous fuels. Among the users of
resid oils are power plants and ocean-going ships. In Southern
California, for example, emissions from ships entering the port of Los
Angeles are considered to be a major cause of regional air pollution.

[0007]Considerable effort has been expended by petroleum refiners to
formulate fuels that reduce emissions. The most common approach to
formulating compliant fuels involves adjusting refinery processes so as
to produce a fuel meeting the specifications set forth by appropriate
government agencies. However, such an approach is difficult for residual
fuels, and the drawbacks to such an approach include high costs in
reconfiguring refinery processes, and possible negative effects on the
quantity or quality of other refinery products.

SUMMARY OF THE INVENTION

[0008]Embodiments of the present invention include systems, methods, and
compositions which may provide improved combustion characteristics of
high-asphaltene carbonaceous fuels. Examples of the combustion
characteristics which may be improved by embodiments of the invention
include one or both of increased combustion efficiency, and reduced
pollutant discharge. Examples of the pollutants which may be reduced
include one or more of ozone, particulate matter (PM), carbon monoxide,
nitrogen oxides (NOx), sulfur dioxide, polynuclear aromatic
compounds, and soluble organic fractions.

[0009]In some embodiments, a fuel additive is provided comprising a plant
extract. In this specification, the term "plant extract" is intended to
broadly encompass extracts of all types of plants, excluding the roots
and bark, and even includes plants such as algae. Suitable plant extracts
are extracts from green and other colored plants as such plants tend to
have high concentrations of desirable extracts. However, even white and
light colored plants include such extracts, though at lower
concentrations. Particularly suitable extracts are from green and other
dark leafy plants such as those from the Leguminosae family which
includes fescue, alfeque, and alfalfa.

[0010]In a preferred embodiment, the plant extract is combined with an
organometallic material. The inclusion of an organometallic compound is
especially useful for treating fuels having particularly high asphaltene
contents in the range of 8 wt. % or higher. Examples of organometallic
materials are hydrocarbon-soluble organometallic compounds that include a
metal selected from the first and second row transition metals. One metal
of particular interest is iron, and particularly suitable organometallic
materials include iron pentacarbonyl, iron naphthenate, ferrocene, and
combinations. The fuel additive may optionally include an oil-soluble
carrier. Examples of suitable oil-soluble carriers include hydrocarbons
such as toluene, aromatic blends, naphthas, gasoline, diesel fuel, jet
fuel, and mixtures thereof. In one embodiment, the oil soluble carrier is
non-oxygenated.

[0011]In certain embodiments, the fuel additive may include other optional
ingredients. Such optional ingredients may include one or more of an
oxygen carrier, a stability aid, a lubricity aid, an anti-oxidant, and a
combustion improver. Meadowfoam oil may be used as a stability aid, an
anti-oxidant, and a lubricity aid. Suitable oxygen carriers include
carotenoids. Examples of antioxidants include 1,2-dihydroquinolines, and
in particular, 2,2,4-trimethyl-6-ethoxy-1,2-dihydroquinoline. Examples of
combustion improvers include compounds known as cetane improvers or
ignition accelerators. Examples of combustion improvers include alkyl
nitrates such as 2-ethylhexyl nitrate.

[0012]In another embodiment of the present invention, a method for
improving the combustion characteristics of a high-asphaltene
carbonaceous fuel comprises adding a fuel additive as described above to
a high-asphaltene carbonaceous fuel prior to or during combustion.

[0013]In another embodiment of the present invention, an additized
high-asphaltene carbonaceous fuel is provided which comprises a
high-asphaltene carbonaceous fuel and a fuel additive as described above.

[0014]In still another embodiment of the invention, a method for preparing
a fuel additive comprises mixing a plant extract with an oil-soluble
carrier and one or more of an organometallic material, an oxygen carrier,
a stability aid, a lubricity aid, an anti-oxidant, and a combustion
improver. In another embodiment of the invention, the fuel additive is
prepared in an oxygen-free or reduced-oxygen atmosphere, and optionally
may include the step of excluding sources of UV radiation during the
preparation. In still another embodiment, non-oxidized oil-soluble
carriers and non-oxidized oxygen carriers are used.

[0015]The plant extract used in various embodiments of the invention may
be obtained by solvent extraction from whole plants using
hydrocarbon-soluble solvents. Polar or nonpolar hydrocarbon-soluble
solvents may be used for the extraction. The extract resulting from the
extraction process is a crude material containing over 300 individual
compounds. In one embodiment, the extract has a paste- or mud-like
consistency that may be described as a solid or semi-solid, rather than a
liquid. Such extracts typically contain chlorophyll A and chlorophyll B
with a higher concentration of chlorophyll A over chlorophyll B. The
color of such an extract is generally a deep black-green with some degree
of fluorescence. Such an extract may be recovered from most plants though
green and darker leafy plants tend to have higher concentrations.
Extracts from plants from the Leguminosae family are suitable. While such
a solid or semi-solid form is generally considered to be preferred for
most embodiments, in other embodiments, a liquid or other form may be
suitable, and may even be preferred. Furthermore, synthetic materials,
for example synthetic carotenoids, chlorophylls, or xanthopylls, may be
used instead of or in addition to natural plant extracts.

[0016]The foregoing has outlined rather broadly the features and technical
advantages of the present invention in order that the detailed
description of the invention that follows may be better understood.
Additional features and advantages of the invention will be described
hereinafter which form the subject of the claims of the invention. It
should be appreciated by those skilled in the art that the conception and
specific embodiments disclosed may be readily utilized as a basis for
modifying or designing other structures for carrying out the same
purposes of the present invention. It should also be realized by those
skilled in the art that such equivalent constructions do not depart from
the spirit and scope of the invention as set forth in the appended
claims. The novel features which are believed to be characteristic of the
invention, both as to its organization and method of operation, together
with further objects and advantages will be better understood from the
following description when considered in connection with the accompanying
figures. It is to be expressly understood, however, that each of the
figures is provided for the purpose of illustration and description only
and is not intended as a definition of the limits of the present
invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]For a more complete understanding of the present invention,
reference is now made to the following descriptions taken in conjunction
with the accompanying drawing, in which:

[0018]FIG. 1 is a plot of NOx emissions measured at the furnace exit
for the various fuel additives used in the EERC Test;

[0019]FIG. 2 is a plot of NOx emissions measured at the baghouse for
the various fuel additives used in the EERC Test;

[0021]FIG. 4 is a plot of heat flux divided by fuel firing rate versus
excess air for the EERC Test; and

[0022]FIG. 5 is a plot of feed rate versus temperature for the EERC Test.

DETAILED DESCRIPTION

[0023]As used in this specification, the term "β-carotene mixture" is
defined as a mixture of from about 89 to about 98% trans β-carotene
with the remainder being from about 2 to 11% of various cis
β-carotene isomers or other poly-unsaturated conjugated
hydrocarbons. An example of such a β-carotene mixture is
ISOMIXTENE®, a product sold by DSM Nutritional Products, Inc. of
Parsippany, N.J.

[0024]Embodiments of the present invention are directed to systems,
methods, and compositions which improve the combustion characteristics of
high-asphaltene carbonaceous fuels. Examples of the combustion
characteristics which may be improved include increased combustion
efficiency, and reduced emissions of one or more pollutants such as
ozone, particulate matter (PM), carbon monoxide, nitrogen oxides
(NOx), sulfur dioxide, polynuclear aromatic compounds, and soluble
organic fractions.

[0025]In one embodiment, a fuel additive comprises a plant extract.
Suitable plant extracts include extracts from green leafy plant material.
Particularly useful plant extracts are extracts from plants of the
Leguminosae family which may include fescue extract, alfeque extract,
alfalfa extract, and combinations thereof. The plant extract may be
provided in an amount such that the high-asphaltene carbonaceous fuel to
be treated includes a plant extract concentration by weight in the range
of about 0.5 ppm to about 10,000 ppm, preferably from about 200 ppm to
about 2000 ppm, and more preferably at about 800 ppm. Without being bound
by theory, it is believed that the oxygen-gathering properties of such
plant extracts provide the beneficial improvements to the combustion of
high-asphaltene carbonaceous fuels such as residual fuel oil and coal.

[0026]The plant extracts may be obtained using extraction methods well
known to those of skill in the art. Solvent extraction methods using
polar or nonpolar hydrocarbon-soluble solvents are generally preferred.
Any suitable extraction solvent may be used which is capable of
separating the suitable fractions from the plant material. Suitable
nonpolar solvents include cyclic, straight chain, and branched-chain
alkanes containing from about 5 or fewer to 12 or more carbon atoms.
Specific examples of acyclic alkane solvents include pentane, hexane,
heptane, octane, nonane, decane, mixed hexanes, mixed heptanes, mixed
octanes, isooctane, and the like. Examples of cycloalkane solvents
include cyclopentane, cyclohexane, cycloheptane, cyclooctane,
methylcyclohexane, and the like. Alkenes such as hexenes, heptenes,
octenes, nonenes, and decenes are also suitable for use, as are aromatic
hydrocarbons such as benzene, toluene, and xylene. Halogenated
hydrocarbons such as chlorobenzene, dichlorobenzene, trichlorobenzene,
methylene chloride, chloroform, carbon tetrachloride, perchloroethylene,
trichloroethylene, trichloroethane, and trichlorotrifluoroethane may also
be used. Generally preferred nonpolar solvents are C6 to C12
alkanes, particularly n-hexane.

[0027]Suitable polar solvents may include, but are not limited to,
acetone, methyl ethyl ketone, other ketones, methanol, ethanol, other
alcohols, tetrahydrofuran, methylene chloride, chloroform, or any other
suitable polar solvent.

[0028]Hexane extraction is a commonly used technique for extracting oil
from plant material. It is a highly efficient extraction method that
extracts virtually all oil-soluble fractions from the plant material. In
a typical hexane extraction, the plant material is comminuted. Grasses
and leafy plants may be chopped into small pieces while seeds are
typically ground or flaked. The plant material may be pelletized to
pellets of ±1/2 to 3/4 inch. The plant material is typically exposed
to hexane at an elevated temperature. The hexane, a highly flammable,
colorless, volatile solvent that dissolves out the oil, typically leaves
only a few weight percent of the oil in the residual plant material. The
oil and solvent mixture may be heated to about or above 100° C. to
remove most of the hexane, and may then be distilled to remove all traces
of hexane. Alternatively, hexane may be removed by evaporation at reduced
pressure. The resulting plant extract is suitable for use in producing
the fuel additives of the present invention.

[0029]Other extraction processes include supercritical fluid extraction,
typically with carbon dioxide, but other gases such as helium, argon,
xenon, and nitrogen may also be used as solvents in supercritical fluid
extraction methods.

[0030]Still another useful extraction process is mechanical pressing, also
known as expeller pressing, which removes oil through the use of
continuously driven screws that crush the seed or other oil-bearing
material into a pulp from which the oil is expressed. Friction created in
the process can generate temperatures between about 50° C. and
90° C., or external heat may be supplied. Cold pressing generally
refers to mechanical pressing conducted at a temperature of 40° C.
or less with no external heat applied. The yield of oil extract that may
be obtained from a plant material may depend upon any number of factors,
but primarily upon the oil content of the plant material. For example, a
typical oil content of vetch (hexane extraction, dry basis) is
approximately 4 to 5 wt. %, while that for barley is approximately 6 to
7.5 wt. %, and that for alfalfa is approximately 2 to 4.2 wt. %.

[0031]Plant oil extracts for use in edible items or cosmetics typically
undergo additional processing steps to remove impurities that may affect
the appearance, shelf life, taste, and the like, to yield a more refined
product. The impurities include may include phospholipids, mucilaginous
gums, free fatty acids, color pigments and fine plant particles.
Different methods are used to remove these by-products including water
precipitation or precipitation with aqueous solutions of organic acids.
Color compounds are typically removed by bleaching, wherein the oil is
typically passed through an absorbent such as diatomaceous clay.
Deodorization may also be conducted, which typically involves the use of
steam distillation. While the extracts used as fuel additives in the
present invention may include such additional processing steps, such
additional steps are generally unnecessary.

[0032]The fuel additive may optionally include an organometallic compound.
Suitable organometallic compounds are hydrocarbon-soluble organometallic
compounds that include a metal selected from the first and second row
transition metals particularly suitable organometallic compounds include
iron pentacarbonyl, iron naphthenate, ferrocene, and combinations. The
inclusion of an organometallic compound is believed to be particularly
useful in improving the combustion characteristics of fuels with
particularly high asphaltene content such as residual fuel oils used in
areas of the world other than North America. The organometallic compound
may be provided in an amount such that the fuel to be treated includes a
concentration by weight of organometallic compound in the range of about
0.5 ppm to about 10,000 ppm as metal, preferably from about 200 ppm to
about 2000 ppm as metal, and more preferably at about 800 ppm as metal.
Without being bound by theory, it is believed that the inclusion of an
organometallic compound provides a catalytic effect to the reactions
promoted by the plant extract material.

[0033]The fuel additive may further comprise meadowfoam oil. Meadowfoam
oil has a number of useful properties, and can function as an oxygen
carrier, a stability aid, and an anti-oxidant. Because the plant extracts
used in the fuel additives of the present invention have oxygen-gathering
properties, and therefore, can be unstable, the inclusion of a material
such as meadowfoam oil can help to maintaining the stability of the plant
extracts and prevent their oxidation.

[0034]The composition may further optionally include at least one carotene
which may be provided in the form of a β-carotene mixture such as
ISOMIXTENE®. Although carotenoids such as β-carotene mixtures
are disclosed, other molecules having extended pi or double bonded
structures of from about 2 to 11 or more conjugated double bonds are also
believed to similarly provide improved combustion characteristics for
resid or other hydrocarbon fuels when used as additives for such fuels.
The moieties of such molecules including the double bond structures can
be terminated by at least one end group further comprising an aromatic,
cyclic, or branched 5 to 8 carbon moiety that is saturated or
unsaturated. Examples include cyclo-pentane, cyclo-pentene, cyclo-hexane,
cyclo-hexene, cyclo-heptane, cyclo-heptene, isopentane or isopentene.
Aromatic structures are considered as extended pi structures also. The
unsaturated/aromatic portions and the end groups can additionally include
various other substituents such as hydroxyl groups, keto groups, alkyl
groups, alkenyl groups and combinations. Additionally, the additive
molecules can comprise from 12 to about 40 or 50 carbon atoms. Such
molecules are found in mixtures of synthetic carotene precursors. Such
additives may be obtained from natural or synthetic sources.

[0035]Furthermore, lycopene is another example of a suitable carotene.
Other suitable carotenoids and carotene precursors are disclosed in
German patent 954,247, issued in 1956 and incorporated by reference.

[0037]Specific antioxidants useful in the present invention are the
quinoline or hydro quinoline compounds such as 1,2 dihydro quinoline
compounds. More particularly,
6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline, commonly referred to as
ethoxyquin, may be used as an antioxidant. Ethoxyquin is sold under the
trademark SANTOQUIN® by Novus International Inc. of St. Louis, Mo.,
and is widely used as an antioxidant for animal feed and forage.

[0038]The fuel additives of the present invention may also contain a
combustion improver such as a cetane improver or ignition accelerator.
Suitable combustion improvers are organic nitrate materials. Preferred
organic nitrates are substituted or unsubstituted alkyl or cycloalkyl
nitrates having up to about 10 carbon atoms, and preferably from 2 to 10
carbon atoms. The alkyl group can be either linear or branched. Specific
examples of suitable nitrate compounds include methyl nitrate, ethyl
nitrate, n-propyl nitrate, isopropyl nitrate, allyl nitrate, n-butyl
nitrate, isobutyl nitrate, sec-butyl nitrate, tert-butyl nitrate, n-amyl
nitrate, isoamyl nitrate, 2-amyl nitrate, 3-amyl nitrate, tert-amyl
nitrate, n-hexyl nitrate, 2-ethylhexyl nitrate, n-heptyl nitrate,
sec-heptyl nitrate, n-octyl nitrate, sec-octyl nitrate, n-nonyl nitrate,
n-decyl nitrate, n-dodecyl nitrate, cyclopentylnitrate,
cyclohexylnitrate, methylcyclohexyl nitrate, isopropylcyclohexyl nitrate,
and the esters of alkoxy substituted aliphatic alcohols, such as
1-methoxypropyl-2-nitrate, 1-ethoxpropyl-2 nitrate, 1-isopropoxy-butyl
nitrate, 1-ethoxylbutyl nitrate and the like. Preferred alkyl nitrates
are ethyl nitrate, propyl nitrate, amyl nitrates, and hexyl nitrates.
Other preferred alkyl nitrates are mixtures of primary amyl nitrates or
primary hexyl nitrates. By "primary" it is meant that the nitrate
functional group is attached to a CH2 group of the amyl or hexyl
group. Examples of primary hexyl nitrates include n-hexyl nitrate,
2-ethylhexyl nitrate, 4-methyl-n-pentyl nitrate, and the like.
Preparation of the nitrate esters can be accomplished by any of the
commonly used methods, such as by esterification of the appropriate
alcohol, or reaction of a suitable alkyl halide with silver nitrate.
These additives can be present the same or different amounts as the other
components of the fuel additive

[0039]The fuel additives may further include a diluent or solvent carrier.
Such a carrier is useful because, in general, low concentrations of the
particular components of the fuel additive are effective in achieving
desirable results, and therefore, the use of a carrier simplifies the
addition of the fuel additive. The use of a carrier can further help to
maintain the components in solution, and can help to prevent oxidation of
the components.

[0040]Suitable solvents for use as the carrier include one or more of an
aromatic hydrocarbon such as toluene or xylene, or other hydrocarbons
such as gasoline, jet fuel, or diesel fuel. In one embodiment, a mixed
aromatic solvent comprising various xylene isomers is used. Examples of
such solvents include those commercially available in North America from
ExxonMobil Chemical and sold under the names AROMATIC 100 FLUID and
AROMATIC 150 FLUID. In one embodiment, a mixture of AROMATIC 100 FLUID
AND AROMATIC 150 FLUID is used.

[0041]When blending the particular components of the fuel additive, it may
be useful to prepare the fuel additive in an oxygen free or low oxygen
atmosphere to prevent oxidation of the fuel additive components.
Optionally, the components may be blended under conditions in which
sources of UV radiation are excluded to further prevent degradation of
the components.

[0042]In those embodiments where the fuel additive includes a plant
extract such as fescue extract, alfeque extract, or alfalfa extract,
meadowfoam oil, and a carotene, the weight ratio of plant extract to
carotene may be from about 50:1 to about 20:1, and preferably is from
about 24:1 to about 10:1. The ratio of grams of plant extract to
milliliters of meadowfoam oil may be from about 12:1 to about 20:1, and
preferably is from about 6:1 to about 10:1. The ratio of milliliters
meadowfoam oil to grams of carotene may be from about 12:1 to about 20:1,
and preferably is from about 6:1 to about 1:1.

[0043]In those embodiments where the fuel additive includes a carotene and
an antioxidant, the ratio of carotene to antioxidant may be from about
20:1 to about 1:1, preferably is from about 15:1 to about 5:1, and more
preferably is about 10:1.

[0044]In another embodiment of the invention, where the fuel additive
includes plant extract and meadowfoam oil, the two may be provided in a
weight ratio from about 1:100 to about 100:1. In an embodiment of the
invention, the concentration of plant extract in the total fuel additive
composition may be from about 0.06 weight % to about 6 weight %, and
preferably is from about 0.12 weight % to about 3 weight %. The
concentration of meadowfoam oil may range from about 0.05 weight % to
about 5 weight % of the total fuel additive composition, and preferably
is about 0.5 weight % of the total fuel additive composition.

[0045]Such fuel additives may be blended into high-asphaltene carbonaceous
fuels such that the plant extract and organometallic material are present
in the fuel in the concentrations set forth above.

[0046]In embodiments in which the fuel additive includes a plant extract,
a non-oxidized carotene, an antioxidant, and meadowfoam oil, certain
factors may be useful in determining appropriate ratios for the
components. Such factors may include the elevation at which the fuel is
to be combusted, the type of engine or device using the fuel, and the
particular fuel properties. Examples of different types of engines or
devices include two-cycle diesel engines and stationary boilers. Examples
of relevant fuel properties include sulfur content, mercaptan content,
olefin content, aromatic content and asphaltene content. For example, if
a fuel has a high sulfur content of 1 wt. % or more, or a high aromatics
content of 25 wt. % or more, the ratios may be adjusted such as to
provide additional plant extract or additional non-oxidized carotene.

[0047]According to another embodiment of the invention, an additized fuel
is provided in which a fuel additive as set forth above is blended with a
high-asphaltene carbonaceous fuel. Formulated fuel compositions according
to embodiments of the invention can further contain other known additives
such as detergents, antioxidants, demulsifiers, corrosion inhibitors,
metal deactivators, diluents, cold flow improvers, and thermal
stabilizers.

[0048]According to another embodiment of the invention, a method for
improving combustion characteristics of a high-asphaltene carbonaceous
fuel comprises the step of adding such a fuel additive to a
high-asphaltene carbonaceous fuel prior to or during combustion.

[0049]Fuel additives of the present invention may be introduced into
residual fuel oil in a number of different ways. For example, the
residual fuel oil to be combusted may be pre-mixed to include the fuel
additive. In another example, the fuel additive is injected into a
residual fuel oil stream being fed to a burner or other combustion
device. In such an embodiment, the fuel additive may be injected using a
metered injection system. Such a metered injection system may optionally
be controlled by a computer system that can optimize the flow of any or
all of the components to the combustion device to optimize its operation.

[0050]For coal, such fuel additives can similarly be added in a number of
different ways. For example, the fuel additive may be sprayed over the
coal prior to combustion. Alternatively, the fuel additive may be pumped
or sprayed into the coal burner along with the coal using a metered
injection system as described above.

EERC Laboratory Testing

[0051]Test runs were conducted at the EERC Laboratory in Grand Forks, N.
Dak. Six drums of residual fuel oil were used in the tests. The residual
fuel oil was supplied by Sun Coast Resources in Houston, Tex. The
properties of the residual fuel oil used are set forth in Table 1. It has
a moderate sulfur content of about 2.63%, with a very high heating value
of 44.5 MJ/kg at a moisture content of 2.40%. The Karl Fischer water
content was determined to be 0.21%. The volatile content of the sample
was determined to be 89.30%, with fixed carbon present at the 8.29%
level. The theoretical emission limit of sulfur dioxide was determined to
be 1714 ppm at a flue gas oxygen concentration of 2.0%. This equates to a
1.18 kg/MJ emission rate for the sulfur dioxide (SO2). The residual
fuel oil had a specific gravity of 0.9952, and the amount of sediment was
determined to be 0.05%. Table 1 also provides the proximate, ultimate,
and heating value analyses for the residual fuel oil tested along with
the theoretical emission limit of sulfur.

[0052]The residual fuel oil was stored cold prior to testing. Barrel
heaters were used to heat the residual fuel oil to 121° C. prior
to transferring it to the feed hopper situated above the pump. A barrel
heater was strapped to the tank of the feed hopper to keep the residual
fuel oil hot during testing, averaging between 113° and
118° C. for use in the test periods shown here. Although the oil
appeared to be rather viscous at this temperature, a homogeneous phase
was maintained so that a readily controllable feed rate to the combustor
was achieved for all test periods.

[0053]The test apparatus at the EERC facility includes a furnace with a
capacity of approximately 19 kg/hr (845 MJ/hr) of residual fuel oil. The
combustion chamber is 0.76 meters in diameter, 2.44 meters high, and
refractory-lined for combustion testing of various types of fuels. The
furnace diameter may be reduced to 0.66 meters to elevate the temperature
entering the convective pass. Furnace exit gas temperatures (FEGTs) as
high as 1400° C. have been achieved during combustion testing in
this mode. However, most tests are performed using the standard
configuration (0.76 meter inside diameter), with the FEGT maintained
between 1100° C. and 1200° C. though the FEGT is typically
raised to between 1250° C. and 1300° C. for the combustion
of residual fuel oil. Two Type S thermocouples, located at the top of the
combustion chamber, are used to monitor the FEGT. They are situated
180° apart at the midpoint of the transition from vertical to
horizontal flow. Excess air levels are controlled manually by adjusting
valves on the primary and secondary air streams. The typical distribution
is 15% primary and 85% secondary to achieve a typical excess air level of
20%.

[0054]When firing liquid fuels such as residual fuel oil, a pump is used
to convey the fuel through a dual-fluid atomizer into the combustion
chamber. Air or steam is commonly used as the atomizing fluid. Combustion
air is preheated by an electric air heater. Heated secondary air is
introduced through an adjustable swirl burner. Flue gas passes out of the
furnace into a 10-inch-square duct that is also refractory-lined. A
vertical probe bank located in the duct is designed to simulate
superheated surfaces in a commercial boiler. After leaving the probe
duct, the flue gas passes through a series of water-cooled,
refractory-lined heat exchangers and a series of air-cooled heat
exchangers before being discharged through either an electrostatic
precipitator (ESP) or a baghouse (BH) for particulate removal.

[0055]At the EERC facility, flame stability is assessed by observation of
the flame and its relation to the burner quart as a function of secondary
air swirl and operating conditions at full load and under turndown
conditions. An International Flame Research Foundation-(IFRF)-type
adjustable secondary air swirl generator uses primary and secondary air
at approximately 15% and 85% of the total air, respectively, to adjust
swirl between 0 and a maximum of 1.9. Swirl is defined as the ratio of
the radial (tangential) momentum to axial momentum imparted to the
secondary air by movable blocks internal to the burner and is used to set
up an internal recirculation zone (IRZ) within the flame that allows
greater mixing of combustion air and fuel. Swirl is imparted by moving
blocks to set up alternate paths of radial flow and tangential flow to
create a spin on the secondary air stream that increases the turbulence
in the near-burner zone.

[0056]At the fully open position of the swirl block, the secondary air
passes through the swirl burner unaffected, and the momentum of this
stream has only an axial component such that the air enters the
combustion chamber as a jet. As the angle of the blocks changes, the air
begins to spin or "swirl" and the radial component of the momentum is
established, creating the IRZ in the near burner region. It is the ratio
of this radial component of the momentum to the axial component that
establishes the quantity defined as swirl.

[0057]The adjustable-swirl burner used by the EERC during flame stability
testing consists of two annular plates and two series of interlocking
wedge-shaped blocks, each attached to one of the plates. The two sets of
blocks can form alternate radial and tangential flow channels, such that
the air flow splits into an equal number of radial and tangential streams
which combine further downstream into one swirling flow. By simply
rotating the movable plate, radial channels are progressively closed and
tangential channels opened so that the resulting flux of angular momentum
increases continuously, between zero and a maximum value. This maximum
swirl setting depends on the total air flow rate and the geometry of the
swirl generator. Swirl can be calculated from the dimensions of the
movable blocks (the ratio of the tangential and radial openings of the
blocks) or from the measurement of the velocity of the air stream
(obtaining both radial and axial components).

[0058]Secondary air swirl is used to stabilize the flame. In the absence
of swirl, loss of flame may result, increasing the risk of dust
explosion. As swirl is applied to the combustion air, fuel droplets are
entrained in the IRZ, increasing the heating rate of the particles and
leading to the increased release of volatiles and char combustion. The
flame becomes more compact and intense as swirl is increased to an
optimum level, which is characterized in the EERC test facility as the
point at which the flame makes contact with the burner quarl. Increasing
swirl beyond this level can pull the flame into the burner region,
unnecessarily exposing metal burner components to the intense heat of the
flame and possible combustion in the coal pipe. Adjustments to the swirl
setting were made manually by moving a lever arm attached to the movable
block assembly. The position of the blocks was noted on a linear scale.

[0059]Increasing swirl to provide flame stability and increased carbon
conversion can also affect the formation of NOx. The high flame
temperatures and increased fuel-air mixing associated with increased
swirl create an ideal situation under which NOx may form. In
full-scale burners with adjustable vanes, swirl is often increased to
reach the optimum condition for carbon conversion, and then decreased
slightly to reduce the production of NOx.

[0060]The general test method at the EERC facility sets the burner at its
maximum level of swirl and monitors system parameters such as fuel feed
rate, excess air, gaseous emissions such as O2, CO2, CO,
SO2, and NOx, combustor static, and air flow rates. Photographs
of the flame and burner zone were taken through a sight port in the
furnace just above the burner cone using standard 35-mm film. Flame
temperature was also measured using a high-velocity thermocouple (HVT) at
a set location in the furnace, and heat flux was monitored using a
baseline heat-flux probe at the same location. An ash sample was
collected at each swirl setting to establish carbon burnout. The swirl
setting was then reduced until the flame was visually observed to lift
off the burner quarl. At this point, the flame was characterized as
unstable under full load conditions which are between 633 and 686 MJ/hr
firing rate. Photographs were again taken to record the flame at this
setting, temperature and heat flux measurements were taken, and an ash
sample was taken once again. Once flame liftoff was established, the
optimum swirl setting was located by visual observation of the flame, and
measurements were recorded once again.

[0061]Flame stability under turndown conditions is characterized by firing
the test fuel at a reduced load, typically one-half to three-quarters of
the full load rate, maintaining the same primary air flow, and adjusting
the secondary air flow to meet excess air requirements. The procedure
described above was used to establish flame stability at reduced load.

[0062]The CTF utilizes two banks of Rosemount NGA gas analyzers to monitor
O2, CO, CO2, and NOx. Sulfur dioxide (SO2) is
monitored by analyzers manufactured by Ametek. The analyzers are
typically located at the furnace exit and the particulate control device
exit. The gas analyses are reported on a dry basis. Baldwin Environmental
manufactures the flue gas conditioners used to remove water vapor from
each gas sample. The flue gas constituents are constantly monitored and
recorded by the CTF's data acquisition system.

[0063]One of the probes used to characterize flame shape and intensity is
the baseline heat-flux probe. The probe uses water to pick up heat from a
2.5 cm-thick stainless steel tip that is inserted into a port in the
sidewall of the radiant zone so that its surface is flush with the inner
wall of the combustion chamber. The water flow rate is measured by
turbine flow meters and the temperature of the water is measured by Type
K thermocouples in the inlet and exit water streams. Two thermocouples
embedded in the outer and inner surface of the probe monitor metal
temperatures. From these values the heat flux is calculated.

[0064]In addition to the baseline heat-flux probe, an HVT was used to
measure the true gas temperature at the same location. The probe is
water-cooled to protect its stainless steel outer shell from the intense
heat of the combustion flame. A Type S thermocouple runs down its center
and is shielded from the radiation of the flame and refractory walls by a
tip made from insulation board. A vacuum pump is used to draw gases past
the thermocouple junction at a rate sufficient to achieve a velocity past
the thermocouple junction of 120 m/sec. At this velocity, the radiative
component to heat transfer is minimized and convective heat transfer is
dominant. In this manner, the true gas temperature can be obtained
without the interference of radiation to or from the thermocouple
junction.

[0065]Fly ash samples were obtained by various means at the inlet and
outlet of the pilot plant ESP or BH. U.S. Environmental Protection Agency
(EPA) Method 5 was used to establish particulate matter (PM)
concentrations in the flue gas. High-volume sample extraction and the
pilot plant control device collection hoppers can provide large samples
for study.

[0066]Residual fuel oil samples were heated to lower the fuel viscosity
prior to atomization in the burner. Fuel additives were added to the
heated fuel stream near the atomizing nozzle by means of a specially
designed metered injection system. In the injection system a fuel flow
meter was used to ascertain fuel flow, the output was fed to a PID
controller which then controlled the flow rate of a chemical metering
pump. The concentration of the fuel additive was dynamically adjusted to
any change in flow rate of the fuel. The output of the metering pump was
injected into the flowing heated fuel producing a dispersion of droplets
of the fuel additive in the fuel. This mixture then traversed a static
mixing section which insured that the treated fuel was homogeneously
mixed with the fuel before entering the atomizing section of the burner.

[0067]Tests were conducted for three days at the EERC facility with a
furnace exit gas temperature (FEGT) between 1250° C. and
1315° C. and at an excess air level at or near 10%. This
corresponds to approximately 2.0% oxygen in the flue gas at the furnace
exit. The residual fuel oil firing rate and the combustion air flow rates
were adjusted during each of these tests to maintain these levels. On the
fourth day, each test performed at an FEGT between 1250° C. and
1315° C. and at an excess air level at or near 5%. Tables 2
through 7 provide baseline and run-average summaries of operating
conditions for each test period during each day of testing. Control of
the residual fuel oil feed rate was accomplished by adjusting the set
point on the speed controller of the pump. The controller then adjusted
pump speed to maintain the feed rate at the desired level. Excess air
levels were achieved by manually adjusting valve positions on each of the
primary and secondary air streams. A BH was used for particulate control
during all test periods.

[0068]The furnace was preheated to 1290° C. with natural gas for up
to 8 hours prior to the start of each day's testing. Furnace pressure was
maintained near -1 torr by adjustment of a control valve blending ambient
air into the duct at the inlet of the induced-draft fan.

[0069]Two banks of analyzers monitored gaseous emissions and were
designated as furnace exit and BH exit in each of the following Tables 2
through 6. Furnace exit analyses were sampled approximately 1 meter
downstream of the fouling probe bank. This oxygen level was used to
control excess air levels during each test. BH exit analyses are normally
obtained from the ductwork following BH. Because of the higher vacuum at
the back end of the test system and the large number of flanged
connections, air leakage into the ductwork resulted in a 1-2% increase in
flue gas oxygen concentrations. The oxygen analysis from each bank of
analyzers was used to correct gaseous emissions of interest to a constant
excess air level of 20% (3.5% O2). The calculation used to correct
emissions levels reported here is:

[0070]Gas analyzers were routinely zeroed and spanned prior to the start
of each test. Additional calibration of the analyzers was performed when
results were suspect or unexpected.

[0071]In Tests AF-CTS-751, 753, 755, 756-1, and 758 (twice), the primary
objective was to establish baseline operating characteristics, emissions
rates for the various gas species, and the work produced under the
various operating conditions. In addition, fly ash samples were collected
to determine the dust loading (or PM) of the gas stream entering the BH.
Results from these tests are provided in Table 2 through 6. Once stable
combustion conditions had been achieved after switching from natural gas
to residual fuel oil, a series of measurements were made using an HVT, a
baseline heat-flux probe, and a small cyclone to obtain fly ash samples.
The swirl setting on the secondary air stream was held constant at 3.5
for all test periods performed during this test series.

[0072]In all other tests, the primary objective was to establish the
effectiveness of various fuel additives for lowering regulated gaseous
emissions and increasing the work produced. The same test protocol was
used here to determine the effectiveness of the fuel additives. Results
from these tests are provided in Tables 2 through 7. As part of the test
protocol, a period of baseline operation typically preceded all test
periods where a fuel additive was evaluated.

[0073]Following are the fuel additive formulations used in this study:

[0082]Initial shakedown testing began the day before actual testing and
included firing the baseline residual fuel oil to establish the
effectiveness of changes that had been made to the system following the
first series of fuel additive tests performed earlier. This shakedown
period verified that the changes made improved the overall operability of
the system. Included among the many changes made were the addition of
insulation to various system feed lines, the piping of steam to the
burner gun for use as the atomizing fluid for the oil, the addition of a
mixing section in the fuel feed line, and the addition of steam heaters
on the storage barrel that was used to fill the feed tank so as to
maintain a residual fuel oil temperature at or near 240° F. The
result of the changes allowed the fuel to be fed continuously through the
burner gun with no carbon deposits forming on the gun or the air piping
within the burner quarl.

[0083]The FEGT was maintained near 2350° F. for all test periods.
In some cases, it was allowed to rise to see the effect of the fuel
additive on the work produced, and in other cases, it was maintained
during fuel additive injection to determine the level of fuel savings
achieved while maintaining the same level of work produced. Because the
changes in fuel and operating parameters provided a very stable
combustion environment, the combustion efficiency was very high for all
test periods. This made it difficult to monitor changes in the combustion
environment resulting from fuel additive addition. Changes in the
combustion environment were noted, though, during this period and are
detailed below. Because of the difficulty of monitoring changes, the
excess air level was lowered to approximately 5% during the final day of
testing on Day 4.

[0084]Two banks of analyzers, one at the furnace exit and one at the BH
outlet, were used to determine the concentration of the combustion
products in the gas stream. Measurements of flue gas O2, CO,
CO2, SO2, and NOx were continuously monitored and recorded
by the CTF data acquisition system. Test period averages have been
provided in Tables 2 through 7.

[0085]Excess air levels fluctuated with changes in the fuel feed rate and
varied from around 9% to 11% during the tests conducted from June 21
through June 23. Corrected SO2 emissions were fairly steady at an
average of approximately 1720 ppm±20 ppm for all test periods near 10%
excess air.

[0086]An analysis of the data indicates that each of the analytical
observables is a strong function of the excess air. When a spline fit is
drawn through the data points, one gets a much better comparison view
than if the data is globally fit. Furnace and baghouse data are treated
separately. Looking at the NOx and CO data for both the furnace and
the baghouse (FIGS. 7 and 8, respectively), one finds that the results
for one of the treated runs are consistently lower than those of the
baseline measurements at equal excess air. Additive 2 shows a consistent
improvement in gaseous emissions. Surprisingly, this fuel additive shows
its effect even though it was only used in experiments with excess air of
about 10%.

[0087]Particulate Matter (PM) emission values measured and expressed as
dust loadings were obtained at the BH inlet during a number of test
periods using U.S. Environmental Protection Agency Method 5 PM sampling.
Such testing provided significant evidence of the effectiveness of
various fuel additives in improving the combustion characteristics of the
residual fuel oil (see FIG. 9). During the baseline test on Day 4 (Test
Period 12), the dust loading entering the BH was determined to be 0.122
g/m3. During Test Period 5, Additive 5 was injected at a rate of 30
mL/hr where EPA Method 5 dust loading was significantly reduced to 0.0677
g/m3, a 44.6% reduction. In Test Period 13, Additive 8 was utilized
at an addition rate of 40 mL/hr as was Additive 10 in Test Period 16. EPA
Method 5 dust loading was reduced during the use of Additive 8 to 0.0886
g/m3 and to 0.0959 g/m3 during the use of Additive 10. This
translates to a 27.5% reduction and a 21.5% reduction, respectively. It
should be noted that the excess air levels during Test Period 5 (Additive
5) were higher than they were for Test Period 12, the baseline test
period, so a portion of the reduction noted here can be accounted for by
the increase in available oxygen. However, this was not the case for Test
Periods 13 (Additive 8) and 16 (Additive 10). Excess air levels were
approximately the same during the baseline test period as they were for
the two noted testing periods.

[0088]While heat flux behavior is a complicated function, it is assumed to
be a function of at least the fuel firing rate and the excess air. FIG.
10 plots the heat flux as measured at EERC divided by the fuel firing
rate versus excess air reported. The data demonstrates that the heat
flux/fuel ratio produced for fuel treated with Additive 2 was greater
than that seen for the untreated fuel. An improvement of from 7.6% to
10.1% in heat flux ratio was seen for Additive 2.

[0089]An infrared (IR) camera/recorder was used to evaluate any changes in
flame temperature that might occur between periods of baseline operation
and fuel additive injection. Results from these measurements have been
summarized in Table 8. It would appear from the data below that the most
telling trend in flame temperature was the oil feed rate. This
relationship can be seen in FIG. 6. The equation of the linear regression
line has been provided and the R2 value calculated. The flame
temperature does not fit a linear relationship with feed rate well, but
does trend in that direction. Although the test furnace was operated at a
similar furnace exit gas temperature during each day of operation, the
corresponding flame temperature varies significantly from day to day, as
does the feed rate required to achieve that temperature. This indicates
that the heat flux through the furnace walls tends to change from day to
day. However, within a single day's operation only small trends may be
noted.

[0090]During the first day of testing, the recorded flame temperature just
prior to fuel additive injection and immediately following injection of
Additive 2 remained constant at 1333° C. The feed rate was also
constant. However, during the second day of testing, the baseline feed
rate (Test Period 4) was considerably higher than during fuel additive
injection. Flame temperature readings from the IR camera were constant at
1402° C. during Test Periods 5 and 7 with the injection of
Additive 5 at the 30 mL/hr and 15 mL/hr rate, respectively. This would
indicate some effect of the fuel additive on heat release in the furnace.
During Test Period 8, Additive 6 was injected at the 40 mL/hr rate. While
the flame temperature decreased to 1392° C., the feed rate was
significantly reduced from baseline levels during this period to 16.23
kg/hr.

[0091]The baseline flame temperature of 1366° C. was achieved in
Test Period 9 with a feed rate of 17.19 kg/hr of residual fuel oil. After
the injection of Additive 7 at the 40 mL/hr rate, the flame temperature
remained constant at a lower feed rate of 16.50 kg/hr. This represents a
reduction in feed of approximately 4%. During the final day of testing,
the initial baseline flame temperature was recorded at 1371° C.
(Test Period 12). Although the temperature dropped to 1359° C.
during the injection of Additives 8 and 9, it remained relatively
constant throughout the day, rising to 1362° C. during the
baseline Test Period 15 that followed. Essentially no change occurred
during Test Period 16 when injecting Additive 10 at the 40 mL/hr rate.
The flame temperature held constant at 1360° C.

CANMET Research Furnace Testing

[0092]Testing was also conducted at the CANMET Research Furnace in Ottawa,
Canada. The residual fuel oil used in the tests was obtained from PROVMAR
Fuels Inc. of Hamilton, Ontario. The properties for the residual fuel oil
are listed in Table 9. Such residual fuel oil has a moderate sulfur
content of about 1.7%, with a very high heating value of 42.12 MJ/kg at a
moisture content of 0.05%. The proximate, ultimate, and heating value
analyses for the residual fuel oil tested are also provided in Table 1
along with the theoretical emission limit of sulfur.

[0093]The residual fuel oil was stored cold prior to testing. A day tank
was used to heat the residual fuel oil to 121° C. and to keep the
fuel hot during testing.

[0094]In this test protocol the furnace control was primarily based on the
fuel flow into the furnace. The fuel flow was held constant along with
the air flow. A calorimetric section of the furnace allowed one to
determine the heat transfer from the furnace as a function of distance
from the burner. There was no "baghouse" in this system and the furnace
exit temperature was allowed to float.

[0095]When firing a liquid fuel such as residual fuel oil, a pump is used
to convey the fuel through a dual-fluid atomizer into the combustion
chamber. In this furnace, compressed air is used as the atomizing fluid.
Combustion air is preheated by an electric air heater.

[0096]Flame stability is assessed by observation of the flame via a quartz
observation port located along the longitudinal axis of the furnace at
the furnace end opposite the burner. Under normal operation a video
camera was used to qualitatively assess the flame quality and to create a
video record of the flame characteristics occurring during an experiment.

[0097]The general test method sets the burner at its maximum level of
swirl and monitors system parameters such as fuel feed rate, excess air,
gaseous emissions (O2, CO2, CO, SO2, and NOx),
combustor static, and air flow rates. Photographs of the flame and burner
zone are then taken through a sight port in the furnace just above the
burner cone using a video camera.

[0098]The CANMET furnace uses two banks of gas analyzers to monitor
O2, CO, CO2, and NOx. Sulfur dioxide (SO2) is also
monitored. The analyzers are typically located at the furnace exit and
the particulate control device exit. The gas analyses are reported on a
dry basis. The flue gas constituents are monitored and recorded by the
data acquisition system at 10 second intervals during the experiment.
Statistical characteristics of the measured quantities were used to
establish confidence limits on the measured data.

[0099]In the calorimetric section of the furnace, inlet and exit
temperatures are monitored at 10 second intervals and recorded by the
data acquisition system. The flow rates of the therminol working fluid
are also measured and accessible via the data acquisition system. From
these measurements the heat transfer in the furnace can be determined as
a function of time for each of the 28 calorimetric bands along the long
axis of the furnace.

[0100]Ash samples were obtained by various means at the inlet and outlet
of the pilot plant ESP or BH. Isokinetic gas sampling is used to
establish particulate matter (PM) concentrations in the flue gas. High
volume sample extraction and the pilot plant control device collection
hoppers can provide large samples for study. Chemical composition was
also determined for the collected ash samples. Collection of the
isokinetic dust samples required approximately 3 hrs per sample. There
was only one ash sample collected per run.

[0101]The residual fuel oil was heated to lower its viscosity prior to
atomization in the burner. Fuel additives were added to the heated fuel
stream near the atomizing nozzle by means of a specially designed metered
injection system. In the injection system a fuel flow meter was used to
ascertain fuel flow, the output was fed to a PID controller which
controlled the flow rate of a chemical metering pump. The concentration
of the fuel additive was dynamically adjusted to any change in flow rate
of the fuel. The output of the metering pump was injected into the
flowing hot fuel producing a dispersion of droplets of the fuel additive
in the warm fuel. This mixture then traversed a static mixing section to
homogeneously mix the fuel additive with the fuel before entering the
atomizing section of the burner.

[0102]Tests performed at the CANMET research furnace were performed with
furnace operation specified by fuel flow rate and excess air level, both
of which were controlled by the furnace operator. The furnace was
preheated with natural gas for up to 5 hrs prior to beginning experiments
on residual fuel oil. Standard start up protocol involved collection of
data with untreated fuel oil burning in the system for at least one hour
prior to beginning any experimental treatment. This protocol enabled one
to verify baseline behavior on each day of operation. The experiments
were designed to investigate the effects of the chemical additives on
furnace operation at two different excess air concentrations (10% and
7.5%). Baseline operation of the fuels was determined at the beginning
and end of test campaigns as well as at the start of each test day.

[0103]In the testing, all of the fuel additives were evaluated at the 10%
excess air level, and only the best performers were evaluated at the
lowered excess air level. The fuel additive compositions for the CANMET
testing were prepared as follows with additives containing
ISOMIXTENE® (Additives 13 and 14) prepared under inert atmosphere in
a glove box, and additives without ISOMIXTENE® (Additives 11, 12, 15,
and 16) prepared under normal atmospheric conditions:

[0104]Additive 11 was prepared by mixing 13.9 grams of fescue extract and
10 mL of meadowfoam oil, and then blending the mixture with AROMATIC 150
FLUID up to 2000 mL.

[0105]Additive 12 was prepared by mixing 13 grams of fescue extract, 10 mL
of meadowfoam oil and 1 mL of SANTOQUIN®, and blending the mixture
with AROMATIC 150 FLUID up to 2000 mL.

[0106]Additive 13 was prepared by mixing 5.12 grams of fescue extract, 5
mL of meadowfoam oil, 10 drops of SANTOQUIN®, and 0889 grams of
ISOMIXTENE®, and blending the mixture with AROMATIC 150 FLUID up to
1000 mL.

[0107]Additive 14 was prepared by mixing 5.13 grams of alfalfa extract, 5
mL of meadowfoam oil, 10 drops of SANTOQUIN®, and 088 grams of
ISOMIXTENE®, and blending the mixture with AROMATIC 150 FLUID up to
1000 mL.

[0108]Additive 15 was prepared by mixing 13 grams of alfalfa extract, 10
mL of meadowfoam oil, and 2 mL of SANTOQUIN®, and blending the
mixture with AROMATIC 150 FLUID up to 2000 mL.

[0109]Additive 16 was prepared by mixing 13 grams of alfalfa extract, and
10 mL of meadowfoam oil, and blending the mixture with AROMATIC 150 FLUID
up to 2000 mL.

[0110]Table 10 summarizes the observations for particulate matter
concentration in the CANMET tests performed at 10% excess air. The carbon
content of the ash collected from the treated fuel experiments were
uniformly lower than that seen in the reference system, but the overall
isokinetic dust loading showed modest increases for Additives 11 and 12.
At a lower excess air ratio the carbon content of the collected ash was
consistent with the isokinetic dust loading as shown in Table 11.
Additive 15 showed consistent reduction in particulate loading.

[0111]Qualitatively, the flames for several of the treated fuels appeared
shorter and brighter than the flames observed for the reference
(untreated) fuels. This observation is supported by the flame video, but
is difficult to quantify. A shorter more dense flame should provide
maximum heat transfer in the calorimetric section of the furnace. Data
supporting this is found in Tables 12 and 13 for experiments performed at
both 10% and 7.5% excess air. Data was collected every 10 seconds to
build a large statistical sample. The standard deviation of this data set
provides an estimate of uncertainty. The measured therminol heat
uncertainty is about 1%. The measured flue gas heat uncertainty is about
0.1%. Heat Disposition changes above 2% are statistically significant at
the 95% confidence level

[0112]Testing was also run at the IPT Laboratory Test Facility in Sao
Paulo, Brazil. The IPT test furnace is operated similarly to that at
CANMET. The IPT test facility employs a horizontal burner, Model MPR,
manufactured by ATA Combustao Tecnica of Brazil that is fitted with an
external water-cooled jacket. The fuel charge rate and excess air of the
flue gas are taken as independent variables and the other observables are
treated as dependent variables. The furnace contains a calorimetric
section. One significant difference in the experiments performed in
Brazil is related to the fuel. Brazilian fuel specifications are
significantly different than those adopted in the United States. For
example, the density and asphaltene content of the residual fuels
commonly used in Brazil are significantly greater than those commonly
used in the United States. At these very high asphaltene and viscosity
levels, pollution caused by unburned carbon (particulate matter) is of
primary importance. Part of the strategy to minimize this problem
involves combusting the fuel under very high excess oxygen conditions.
Standard operating procedure in Brazil calls for operating a furnace at
furnace exit oxygen content of about 7% or about 37.5% excess air.

[0113]The fuel additive evaluated at IPT contained a combination of plant
extract and an organometallic iron complex. In particular, 49.2 grams of
alfalfa extract were mixed with 7.57 mL of SANTOQUIN® antioxidant,
and 37.9 mL of meadowfoam oil. The mixture was combined with AROMATIC 150
FLUID up to 3785 mL, and 600 mL of the resulting mixture was further
mixed with 117 grams of iron naphthenate and 190 mL of iron
pentacarbonyl. This formulation was prepared under normal atmospheric
conditions with the iron naphthenate transferred anaerobically using a
syringe. The iron content of the resulting solution was 6 wt. %. The
residual fuel oil tested at IPT was additized with this additive at 813
ppm.

[0114]Table 14 shows particulate matter concentrations observed under
treated and untreated conditions. The reduction in particulate matter is
very significant at both 4.5% and 7% oxygen levels, but perhaps the more
significant observation is that the particulate matter concentration
observed under treated conditions for both the oxygen concentrations are
very close. It is well known that under high excess oxygen combustion
conditions, a significant fraction of the heat is lost to the flue gas.
The tests showed that by shifting from 7.0% excess oxygen to about 4.5%
excess oxygen, a 17% improvement in useful heat was realized. Using the
fuel additive tested, this increase in efficiency was accompanied by a
43% decrease in particulate matter emissions.

[0115]Although the present invention and its advantages have been
described in detail, it should be understood that various changes,
substitutions and alterations can be made herein without departing from
the spirit and scope of the invention as defined by the appended claims.
Moreover, the scope of the present application is not intended to be
limited to the particular embodiments of the process, machine,
manufacture, composition of matter, means, methods and steps described in
the specification. As one of ordinary skill in the art will readily
appreciate from the disclosure of the present invention, processes,
machines, manufacture, compositions of matter, means, methods, or steps,
presently existing or later to be developed that perform substantially
the same function or achieve substantially the same result as the
corresponding embodiments described herein may be utilized according to
the present invention. Accordingly, the appended claims are intended to
include within their scope such processes, machines, manufacture,
compositions of matter, means, methods, or steps.